Olefin hydrocarbons are valued for the production of a variety of materials, including many petrochemicals. In some dehydrogenation processes, short chain saturated hydrocarbons are modified to form a corresponding olefin. A particularly useful olefin is propylene, which is produced by dehydrogenation of propane. Propylene is an enormously useful petrochemical commodity with demand steadily growing. Propylene is used in the production of polypropylene, acrylonitrile, acrylic acid, acrolein, and many others useful compounds. Polypropylene is widely used in many consumer and industrial products.
Propane dehydrogenation processes that produce olefins such as propylene may include feeding propane to a dehydrogenation unit where it is dehydrogenated using a catalyst to form propylene. A compressor compresses the effluent from the dehydrogenation unit to a high pressure to recover unreacted propane and propylene in a recovery section. The compressed reactor effluent is chilled to maximize propane and propylene recovery.
The hydrocarbon product stream may be communicated from the recovery unit to a de-ethanizer distillation column where ethane and lighter components are recovered as an overhead gas, and propane and propylene, and heavy boiling compounds are removed as bottoms. These bottoms are then communicated to a propylene splitter distillation column where propylene is recovered as an overhead liquid and unreacted propane from the bottoms may be recycled back to the dehydrogenation unit.
These processes often require significant energy input to boil, pressurize and otherwise process the various steps. The significant energy demands lead to high costs and other disadvantages.